#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<iostream>
using namespace std;
int add(int x = 70, int y = 60, int z = 50)
{
	int m;
	if (x > y)
		m = x;
	else
		m = y;
	if (z > m)
		m = z;
	return m;
}
int main()
{
	int s1 = 0, s2 = 0, s3 = 0;
	s1 = add(10, 20, 30);
		cout << "s1=" << s1 << endl;
		s2 = add(10, 20);
		cout << "s2=" << s2 << endl;
		s3 = add();
		cout << "s3=" << s3 << endl;
	return 0;
}